Difference between non-woven and woven geotextiles
Geotextiles are geosynthetic materials designed specifically for construction and engineering projects. These robust synthetic fabrics are manufactured for uses like soil stabilization, erosion control, construction, drainage, and many such geotechnical projects. They are typically made from either polypropylene or polyester. The most common types of geotextiles are woven and non-woven fabrics.
What is a woven geotextile?
Woven geotextiles are produced when single yarns are woven together in a loom. This yields tough and durable geo-fabrics that are used for roadways, driveways, residential streets, and highway applications. Although it’s less porous than other types, woven geotextiles serve long-term separation and reinforcement needs. Its chemical resistance ensures durability in even adverse chemical environments.
What are the functions of woven geotextiles?
- Reinforcement: Woven geotextiles use their high tensile strength to reinforce soil. They absorb tensile forces, improving the soil’s shear strength and overall stability. This allows for steeper slopes, stronger foundations, or thinner road bases.
- High load support: These materials are particularly valuable when dealing with heavy loads. For example, a busy highway or an area where heavy machinery operates regularly. The woven geotextile spreads out these concentrated forces over a wider area of the underlying soil, preventing the ground from getting compressed and developing ruts or settling unevenly. Instead of the weight punching through weak spots, it gets distributed more evenly, which means the structure lasts longer and performs better under stress.
- Permeability: Woven geotextiles permit limited flow perpendicular to their plane (low permittivity). However, their relatively small pore openings can become clogged by fine soils, making them less suitable for applications that require continuous or high-volume drainage.”
- Tensile strength: Tensile strength is how hard you can pull on a geotextile before it snaps. It’s basically the material’s breaking point under tension. This matters because in construction, these materials face constant stress from soil movement and heavy loads. If you pick a geotextile that’s too weak for the job, it’ll tear and your project fails. Heavy-duty work like highways needs high-strength materials, while lighter projects can use something less robust. Getting the strength right from the start prevents problems and saves money
Applications of woven geotextiles
Woven geotextiles are a material of choice for their three inherent material properties, which are mechanical, chemical, and physical. These material features make geotextiles a preferred choice to use in a number of industries, where construction needs to be optimized.
- Highways: Woven geotextiles work like a strong fabric layer underneath roads and highways. They keep the road base materials from mixing with the softer soil below and stop everything from shifting around when heavy trucks roll over. This simple barrier makes the pavement last much longer and prevents those annoying potholes and cracks that develop when the foundation isn’t stable. For controlling erosion on hillsides though, you’d want to use non-woven geotextiles or special erosion blankets instead – they’re better suited for that job. While woven geotextiles allow some water to pass, they are not chosen for their drainage or filtration capabilities in road systems. A non-woven geotextile is almost always specified for filtration to prevent clogging and ensure long-term drainage performance.
- Parking lots: Parking lots withstand repetitive and localized loading, as well as extreme temperature variations. Paving fabrics, which are typically specialized non-woven geotextiles saturated with asphalt, are used to reduce reflective cracking and protect the pavement. In contrast, woven geotextiles are placed beneath the pavement layers to reinforce the aggregate base and separate it from the subgrade. Woven geotextiles, when deployed correctly, significantly reduce settlement and extend the lifespan of parking lots by reinforcing the base course.
- Basal reinforcement for embankment over soft soil: Woven geotextiles improve the distribution of loads applied to the embankment structure reducing the excessive settlement or failure of the soft soils. This creates an even distribution of loads over a larger area, thus minimizing the local stress concentrations that otherwise lead to deformation. By improving tensile strength, the woven geotextiles enhance the shear resistance by acting as a reinforcement layer and prevent sliding or slumping.
- Load Transfer Platforms (LTP): For LTPs, woven geotextiles are a secondary product. In that, geogrids are for reinforcement. Woven geotextiles are suggested as a combination product, for separation and to improve the lateral restraint but are not typically the main reinforcing element.It also creates a stiffening effect that resists the compression of the granular layers above it. The separation function prevents the mixing of the granular fill with the subgrade, but a non-woven geotextile is often used in conjunction when high filtration performance is required to prevent clogging.
What is a non-woven geotextile?
Non-woven geotextiles are manufactured by needling the fibres, among other mechanical entangling forms. They are mainly made from synthetic polymers, including polyester & polypropylene, and their strength can be improved through heat treatment (calendering), which bonds the fibers together. However, this process typically reduces permeability. The inherent high permeability of non-woven geotextiles comes from their random, porous fiber structure created during needle-punching. Non-woven geotextiles are often used in projects for protection, filtration, separation, and drainage.
What are the functions of the non-woven geotextiles?
- Filtration: Non-woven geotextiles perform well when it comes to filtration processes. They allow fluid to pass through a porous structure while retaining solids and contaminants, making them useful in water filtration, wastewater treatment, and soil erosion control.
- Separation: Non-woven geotextiles excel at separation, which means preventing two distinct soil or aggregate layers from mixing. By keeping these layers separate, the geotextile makes sure each material can do its job properly. This stops the weak soil underneath from mixing with the strong gravel above, thereby preserving the road’s strength. In applications like landfills engineering, non-woven geotextiles separate different layers within the liner or cap system and often protect the primary impermeable barrier from damage, rather than acting as the impermeable barrier themselves.
- Drainage: The porous nature of non-woven geotextiles facilitates drainage. They are indispensable as drainage to regions lacking good soil conditions and excessive moisture. Such materials are frequently used in landscaping, construction, and agriculture.
- Permeability: Outstanding permeability is among the critical effective properties in describing non-woven geotextiles. This immediately conveys that fluid can pass directly through such fabric.
- Weight classification: Non-woven geotextiles are generally classified by weight per unit area. It is important to consider in selecting geotextiles for an application, as weight will affect a whole host of other things, including, but not limited to, strength and permeability for a given fabric.
Applications of non-woven geotextiles
- Under rock riprap revetments: Non-woven geotextiles are also placed under rock riprap revetments, acting as a filter to hold the soil in position and prevent it from clogging the voids between the rocks due to soil washing. This protects the revetment structure, keeping soil erosion beneath the revetment at bay.
- Enveloping French drains: Non-woven geotextiles are most commonly used to envelop French drains. This protects against the drain getting clogged by filtering soil particles, increases drainage for water flow with a smoother path for the movement of water, and prevents possible erosion around the drain.
- Alternative subsurface drainage solutions: Non-woven geotextiles are used to wrap or work in conjunction with drainage systems, such as perforated pipes (in French drains), to act as a filter. They can replace graded aggregate filters, but do not replace the drainage pipes or geocomposite drains (like wick drains) themselves. This will prevent drainage systems from clogging, increase the flow of water through the systems, and aid in preventing erosion around them.
How is a non-woven geotextile different from a woven geotextile?
- Application: Woven geotextiles are primarily used for reinforcement and stabilization, which is caused by their high tensile strength and durability. They are particularly suitable for roadways & embankments, where structural integrity is necessary. On the other hand, non-woven geotextiles are better suited for applications requiring filtration, separation, and drainage. Their high permeability makes them ideal for water filtration, erosion control, & as a protection layer for impermeable landfill liners.
- Manufacturing: Woven geotextiles are produced using a loom that weaves individual yarns into a structured fabric. This method gives them a more defined structure and more tensile strength. Non-woven geotextiles are manufactured by bonding using techniques like needle-punching or heat treatment. It is suitable for a low -low-structured but more permeable fabric, fluid movement, and filtration.
- Properties: Woven geotextiles are known for their high load-bearing capacity and tensile strength, making them ideal for applications requiring tough and durable materials. Non-woven geotextiles are generally more porous, allowing higher water flow-through rates. This makes them more effective for filtration and drainage tasks. In contrast, the tighter structure of woven fabrics limits permeability but increases mechanical strength.
- Materials: Both types of geotextiles are made from tough plastic materials – usually polypropylene or polyester. Engineers pick between these based on what the project needs. Some materials handle acidic or alkaline conditions better. Others resist stretching over time when constantly loaded. While some hold up better against sun damage during installation.
It really comes down to matching the right type to your job. Need something strong to reinforce soil or hold heavy loads? Go with woven geotextiles. Need to filter water, keep different materials separate, or help with drainage? Non-woven is your best bet.